To find the motorway clear, perhaps, is a marvel! (7)
I believe the answer is:
miracle
'a marvel' is the definition.
(I've seen this before)
'to find the motorway clear perhaps' is the wordplay.
I cannot quite understand how this works, but
'motorway' could be 'mi' (resembles M1, English motorway) and 'mi' is located in the answer.
an anagram of 'clear' is 'racle' which is present in the answer.
No letters remain.
This explanation may well be incorrect...
'is' acts as a link.
Can you help me to learn more?
(Other definitions for miracle that I've seen before include "Inexplicable wonder" , "Remarkable occurrence" , "God-inspired event" , "Supernatural occurrence" , "Divinely-inspired event" .)